Patent GB-389820-A (GB)
Title: Improvements in or relating to automatic switches for use in telephone or like systems
IPC: H01H67/16
Filed: 1931-09-21
Abstract: 389,820. Automatic exchange switches. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. Sept. 21, 1931, No. 26380. Convention date, Sept. 29, 1930. [Class 40 (iv).] A two-directional ratchet-driven switch comprises the following features : (1) Restoration of the switch shaft in the longitudinal direction is effected by a spring-controlled pivoted arm engaging the end of the shaft, the release magnet when operated withdrawing simultaneously operating and holding pawls' from both longitudinal and rotary ratchets. (2) The operation of longitudinal off-normal springs at various levels is effected by angularly-adjustable cams driven through gearing and controlled by the pivoted release arm. (3) Rotary offnormal and eleventh-step springs are controlled by an arm on a pivoted member, the arm being permitted to move to a limited extent on the first rotary step and to a greater extent on the eleventh rotary step under the control of a cam on the switch shaft, means being provided whereby the eleventh-step springs may be operated only on desired levels. (4) Longitudinal off-normal springs and springs closed during operation of the release magnet are controlled by a single member moved partially on the first longitudinal step and having an interlocking relationship with the releasemagnet armature whereby it moves further when the magnet operates and then locks the armature operated until release of the shaft is complete. (5) The switch mechanism has a pin-and-slot connection with the rack and is looked in position by a lug on the switch engaging a hole in a spring attached to the rack. (6) A jack assembly on the rack has its units held together by screws which also serve to fix the assembly to the rack. Switch construction. The switch comprises a cast portion 150, Figs. 7 (front), 12 (right side), and 18 (top), and a sheet-metal portion, Fig. 7B, attached by top and bottom plates 125, 126 to the casting 150. The sheet-metal portion is perforated to receive relays and condensers which are thus located to the right of the switch mechanism. The switch shaft 500 is mounted horizontally the wipers being arranged at the left-hand end which projects through a wall of the casting as shown in Fig. 1. The wipers are carried by insulating brackets 6101 adjustably clipped to the shaft, the line wipers 333, 334 being separated by an insulation-covered metal spacer 609. The wiper cords pass to a terminal block 910, Fig. 7, through a slot 151 in the wall of the casting. The shaft 500 carries a longitudinal ratchet bar 610, secured at its ends by screws 375, 376, and actuated by a pawl 611 on the armature 540 of primary magnets 378, Fig. 18. A spring 662 controlled by screw 664 serves as a forward-stop for pawl 611, whilst a slotted cam member 612, Fig. 11, provides an adjustable back-stop for the armature 540. The rotary ratchet 640 is keyed to the shaft by a notch 643, Fig. 21, engaging the ratchet bar 610, and is actuated by armature 545 through pawl 637. Both armatures 540, 545 are pivotally mounted on pins keyed to the casting, and have means for adjusting the air gap. Fig. 23 shows the method of attaching the rotary restoring spring in a manner which permits ready adjustment of the tension. The spring is attached at one end to the ratchet 640 and at the other end carries a button which fits into a notch 650 in a screw 645 which is locked to the casting 150 in any desired position by a nut 383. During the rotary movement, the shaft is held against longitudinal release by the engagement of the bar 610 with a circular notch 680 in a plate 700. The release of the switch is effected by energizing magnet 615, a projection 5482 on the armature of which withdraws the longitudinal operating and holding pawls 611, 613, whilst another projection 548<1> through a sliding bar 710, Fig. 12, actuates a projection 655<1> which effects the withdrawal of the rotary operating and holding pawls. The shaft 500 then returns to normal under the action of a spring-controlled arm 614 pivoted on a shaft 505, the free end of the arm pressing against the right-hand end of the shaft 500. Off-normal and magnet-controlled contact springs. Ordinary off-normal springs 207, Fig. 12, are controlled by a projection 614<1>, Fig. 14, on release arm 614 acting through a pivoted lever 617. Longitudinal off-normal springs actuated at particular levels are controlled by cams 625, 626, Fig. 16, each securable to a shaft 529 in any one of ten positions as desired. The shaft 529 carries a pinion 621 meshing with a sector 622 mounted on the shaft 505, the sector moving in' accordance with the longitudinal movement of the shaft by means of a locking connection with arm 614. The rotary off-normal springs 316 and eleventh-step springs 309, Fig. 18, are controlled by an arm 647 on a comb member 653, Figs. 7 and 21, pivoted on a pin 536. At the first rotary step, cam 568 permits lever 657 to rock pin 536 sufficiently for springs 316 to be operated. At the eleventh rotary step, cam 568 moves clear of lever 657 so that pin 536 is free to move further 'and a pin 660 on the ratchet bar 610 acts through one of the teeth of the comb 653 to cause arm 647 to operate springs 309. By breaking off certain teeth of the comb, the eleventh-step springs may be arranged to operate only on particular levels. Springs 209, Fig. 12, are closed by the operation of the release-magnet armature through a pivoted lever 628. In a modification, Figs. 26 and 26A, the spring 802 controlling the ordinary off-normal contacts moves away from spring 801 but the contacts controlled by the latter are not operated until the release magnet operates when a projection 5491 enters an aperture in the spring and maintains the armature locked until spring 802 restores when the shaft reaches normal. Racks, construction of and arrangement of apparatus on. Switch bases 109 are attached back to back on either side of an I-beam 101, Fig. 1, with intervening fibre insulation strips 102. The bases have forwardly-extending portions, Fig. 6, with extensions 106<1>, 106<2>, to which the switch banks are fixed. The switch mechanism is fitted to the base 109 with notches in the plates 125, 126, engaging pins 501, 504, and is locked in position by a lug 3371 engaging a hole in a spring 337. A jack assembly, Fig. 5, is fitted in opening 113, Fig. 6, the jack units being held in position between combs 601, 602 by screws 350, the heads of which register with notches on one side of opening 113 whilst the other ends register with notches on the other side, the whole being held tightly by nuts 351.